The Greensand Ridge, also known as the Wealden Greensand is an extensive, prominent, often wooded, mixed
greensand/
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicat ...
escarpment in south-east England. Forming part of
the Weald, a former dense forest in Sussex, Surrey and Kent, it runs to and from the
East Sussex coast, wrapping around the High Weald and Low Weald. It reaches its highest elevation, , at
Leith Hill in Surrey—the second highest point in
south-east England, while another hill in its range,
Blackdown, is the highest point in
Sussex at . The eastern end of the ridge forms the northern boundary of
Romney Marsh
Romney Marsh is a sparsely populated wetland area in the counties of Kent and East Sussex in the south-east of England. It covers about . The Marsh has been in use for centuries, though its inhabitants commonly suffered from malaria until ...
.
About 51 per cent of the Wealden Greensand is protected as the
South Downs National Park,
Kent Downs Area of Outstanding Natural Beauty and
Surrey Hills Area of Outstanding Natural Beauty.
Geology and soils
Geological history
The Greensand Ridge, formed of
Lower Greensand, much of which is sandstone and where hardest is locally termed
Bargate stone, is a remnant of the Weald dome, part of the great
Weald-Artois Anticline that runs from south-east England into northern France.
The Weald dome consists of a series of geological strata laid down in the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
that have subsequently been lifted up, formed into a dome (i.e. anticline) and then deformed and faulted. The top-most and therefore youngest layer of the dome is
Chalk
Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. C ...
, laid down in the
Upper Cretaceous. Below it lie successively older strata of alternating clays and sandstones laid down in the
Lower Cretaceous, namely
Upper Greensand,
Gault Clay,
Lower Greensand,
Weald Clay and the
Hastings Beds. Differential fluvial erosion has virtually flattened the dome into a series of hills and vales. On the surface the strata of which the dome is composed crop out in a series of concentric circles, shaped like a horseshoe, with the more resistant chalk and sandstones forming hills and ridges (such as the North and South Downs, the Greensand Ridge, and the High Weald), and the weaker clays forming vales (such as the
Low Weald) between them. The very resistant rocks of the Lower Greensand, in particular the Hythe Beds, have produced prominent escarpments that form an arc around the northern edge of the Low Weald, running parallel to and just south of the chalk escarpment of the
North Downs. This stretch of the Greensand has become the most closely identified with the term "Greensand Ridge", and it includes the second highest point in south-east England,
Leith Hill in Surrey. West of the Weald the Lower Greensand has produced a more extensive area of hills and valleys, including the highest point in Sussex,
Blackdown. On the south side of the Weald the Lower Greensand also forms another arc of rather less pronounced hills parallel to and just north of the
South Downs, which become less prominent the further east one goes.
Geology
The Lower Greensand is a predominantly
arenaceous sandstone consisting of sediment that accumulated apparently in a shallow sea in the later part of the
Lower Cretaceous. It also contains important subsidiary elements of silty and argillaceous material. Chert, ironstone and calcareous deposits occur in small amounts. When fresh the rocks have a greenish colouration owing to the presence of
glauconite, but on exposure to the atmosphere this is rapidly oxidised to limonite, giving rise to a yellow or reddish brown staining.
The Lower Greensand is composed of alternating mudstones (sandy, with clay particles such as
smectite) and sandstones, up to a maximum thickness of about , and is composed of a number of distinct formations, namely the Folkestone Beds, Sandgate Beds, Bargate Beds, Hythe Beds and Atherfield Clay.
Soils
The soil of the Greensand is quite varied, ranging from fertile to fairly sterile. On the fertile soils we see
chestnut and stands of
hazel and
oak, while
Scots Pine and
Birch
A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech- oak family Fagaceae. The genus ''Betula'' cont ...
colonise the poorer soils.
[Greensand Way in Kent, 1992, Kent Count Council, ]
Relief and drainage
Broadly speaking, the Greensand Ridge runs along the northern edge of the Weald in a west-east arc from Surrey into Kent, just south of and parallel to the chalk escarpment of the North Downs. The ridge is separated by a mixed deep and shallow, fertile depression from the North Downs referred to as the '
Vale of Holmesdale', formed on Gault Clay, and a narrow band of Upper Greensand that outcrops at the foot of the chalk scarp (ridge). In some places the clay vale is very narrow: for example at Oxted the gap between summits of the Greensand Ridge and the North Downs is less than .
The Greensand Ridge, capped by the resistant sands and sandstones of the Hythe Beds, reinforced by bands of
chert
Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a ...
, rises steeply as a series of high, wooded escarpments between
Gibbet Hill, Hindhead (), north of Haslemere, and the ridge's highest point,
Leith Hill (). It then flattens for several miles, before re-emerging east of Nutfield to run eastwards as a high wooded ridge into an area between Oxted and Sevenoaks known locally as the ''Chartlands'', where it reaches another high point at
Toys Hill
Toys Hill is a hamlet which lies within Brasted civil parish in the Sevenoaks district of Kent, England. It lies to the south of Brasted Chart, also in the parish.
The hamlet is situated on the steep scarp slope of the Greensand Ridge, a promine ...
, Kent (). Here there are views to the south of the Weald from a terrace donated in 1898 by
Octavia Hill, one of the founders of the
National Trust. The ridge continues eastwards past Sevenoaks, until south-west of
Maidstone it is broken by the valley of the
River Medway. The ridge then continues as far as
Pluckley, Kent. From there the land levels until it drops to the old sea-cliff line above Romney Marsh.
In the area around Haslemere local anticlinal features are superimposed on the main axis of the Wealden anticline, causing the outcrop of resistant Hythe Beds to widen from to more than and to produce an escarpment that is particularly marked between Haslemere and Midhurst, where Blackdown rises to , the highest point in Sussex. South of here the Vale of
Fernhurst has been eroded down into the Low Weald by what is now a small stream following a line of a gentle west-east trending upfold. This stream, the
River Lod, runs parallel to the larger
River Rother which flows about 10 km further south in the lee of the chalk escarpment of the South Downs. Valley slope processes in the Vale of Fernhurst have resulted in escarpments to the north and south that are steep enough to have collapsed by land slipping. Further east, the Lower Greensand has not produced any pronounced topographical features.
In many places along the escarpment of the Greensand Ridge erosion by wind and rain, landslips on the steep scarp face, and
solifluction in glacial times have further combined to create steep-side coombes, and low hillocks below the scarp.
Relationship to the Weald
The Greensand Ridge is sometimes associated with the
Weald; the ridge forms the high border of area of the Weald.
The Jutes and Saxons who settled in south-east England in the centuries following the collapse of the Roman empire applied the term ''Weald'' (a Germanic term for woodland) to the very large, heavily wooded forest that they found lying inland of the coastal lands and river valleys that they initially settled. This forest, difficult to penetrate and settle, and difficult to exploit agriculturally, in due course became an essential part of a system of
transhumance whereby each autumn swine would be driven, sometimes over long distances, from the longer-settled areas on the periphery into the Wealden forest to feed on acorns of oak trees and beech mast. For these peoples the term ''Weald'' did not include the land cleared of forest and settled earlier, such as the fertile
Vale of Holmesdale (which separates the North Downs from the Greensand Ridge), nor the more lightly wooded and open hills found on the sandstones of the Greensand Ridge, which also seem to have been settled earlier. Local people regarded the hills of the Greensand Ridge as overlooking the Weald, rather than forming a part of it, and hence a distinction came to be made between the settlements on the Greensand Ridge, such as Sevenoaks, Sundridge Upland and Boughton Malherbe Upland, and those formed during the later medieval colonisation of the Wealden portion of these parishes, called today Sevenoaks Weald, Sundridge Weald and Boughton Malherbe Weald.
A practice of treating the Greensand Ridge regularly as part of the Weald arose in geology when natural scientists, starting in the late 18th century, began to include it in their analysis of the geological history of the Wealden dome. Geology still confuses by using interchangeably the Weald and the "Wealden Anticline" that embraces all the land bounded by the chalk escarpments of the North and South Downs, including the Greensand hills.
Economic exploitation
The Folkestone Beds consist of seams of pebbles and sand. It is from here that the stone known as chert is found, familiar in the High Chart hills around
Limpsfield
Limpsfield is a village and civil parish in Surrey, England, at the foot of the North Downs close to Oxted railway station and the A25. , Surrey. In Surrey the Sandgate Beds and Bargate Beds, which lie on top of the Hythe Beds, have yielded a distinctive yellow stone seen in many local buildings. Ironstone, from layers embedded in the Sandgate Beds, is often seen in chips (
gallets) pressed into the mortar between such stones. To the east, especially around Maidstone, Kent, the Hythe Beds yield a blue-grey sandstone with a high lime content. Known as ragstone, this is seen in many local buildings.
Fuller's earth
Fuller's earth is any clay material that has the capability to decolorize oil or other liquids without the use of harsh chemical treatment. Fuller's earth typically consists of palygorskite (attapulgite) or bentonite.
Modern uses of fuller's ea ...
, which lies interbedded between the Bargate and Sandgate Layers, was much quarried for the cloth industry. The seam, which lies about 20 to 30 feet below the surface between Nutfield and Bletchingley, was considered the best in the country and for several centuries large quantities were excavated. Resources are now running low and little is now extracted.
[Cowan (1997), p.41.]
Settlements
Principal settlements lying on the southern part of the Greensand in Sussex, adjacent to the South Downs, include
Storrington
Storrington is a small town in the Horsham District of West Sussex, England, and one of two in the civil parish of Storrington and Sullington. Storrington lies at the foot of the north side of the South Downs. it has a population of around 4,6 ...
(at the eastern end of the ridge) and
Midhurst.
Petersfield marks the western end, where the ridge turns north east. Settlements on the main part of the ridge, running from Surrey into Kent include
Haslemere,
Godalming,
Reigate and
Redhill,
Oxted
Oxted is a town and civil parish in the Tandridge district of Surrey, England, at the foot of the North Downs. It is south south-east of Croydon in Greater London, west of Sevenoaks in Kent, and north of East Grinstead in West Sussex.
Oxt ...
and
Sevenoaks.
Recreation
Much of the ridge in Surrey and Kent is followed by a long-distance walking route, the
Greensand Way. Extending for 108 miles, it starts in the west at
Haslemere and ends in the east at Ham Street, Kent, on the edge of Romney Marsh. The route passes through or close to Godalming,
Cranleigh,
Dorking, Reigate, South Nutfield, Oxted,
Westerham,
Sevenoaks,
Maidstone and
Ashford Ashford may refer to:
Places
Australia
*Ashford, New South Wales
*Ashford, South Australia
*Electoral district of Ashford, South Australia
Ireland
*Ashford, County Wicklow
*Ashford Castle, County Galway
United Kingdom
*Ashford, Kent, a town
**B ...
.
Statutory designations
The south-west part of the Greensand ridge and hills is in the
South Downs National Park. Much of the Greensand Ridge in Surrey is one limb of the
Surrey Hills Area of Outstanding Natural Beauty while a section of the Greensand hills in western Kent, from Limpsfield Chart near
Westerham through Sevenoaks to
Plaxtol
Plaxtol is a village and civil parish in the borough of Tonbridge and Malling in Kent, England. The village is located around north of Tonbridge and the same distance east of Sevenoaks. In the 2011 Census, the parish had a population of 1,1 ...
, forms part of the
Kent Downs Area of Outstanding Natural Beauty, where it is known as the ''Sevenoaks Greensand Ridge''.
Principal summits
Hills on the Greensand Ridge at least 200 metres high and with 30 metres or more of
topographical prominence are here listed, along the range from west to east.
References
Bibliography
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*
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{{Surrey Hills AONB
Geology of England
Hills of Hampshire
Hills of Kent
Hills of Surrey
Ridges of England